Reinforced secondary backing fabric and method of using the same

ABSTRACT

A reinforced secondary backing and method of using the same, in which the reinforced secondary backing includes reinforcing yarns interconnect to the secondary backing fabric. The reinforcing yarns generally extend in the longitudinal or warp direction and provide additional surface area to which an adhesive may bind when combining the reinforced secondary backing to a primary backing in forming a laminate carpet. The reinforcing yarns may be spaced across at least a portion of the backing uniformly, concentrated in an area that typically displays weakness (such as adjacent the edges of the carpet), or a combination thereof. It is noted that this abstract is provided to comply with the rules requiring an abstract that will allow a searcher or other reader to ascertain quickly the subject matter of the technical disclosure and is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.

RELATED APPLICATION

This patent application is a divisional of U.S. patent application Ser.No. 10/655,355, entitled “Reinforced Secondary Backing Fabric and Methodof Using the Same,” filed on Sep. 4, 2003 and assigned to the sameassignee as this application. The aforementioned patent application isexpressly incorporated herein, in its entirety, by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a reinforced secondarybacking and, more particularly, to carpets that use the reinforcedsecondary backing and a method of forming a carpet with that reinforcedsecondary backing.

2. Background

Laminate carpets typically include a secondary backing forming theirlower surface and a primary backing tufted with yarns forming theirupper surface. Latex is often the adhesive used to bond the primary andsecondary surfaces together. That latex, or binder, is usually appliedbetween the primary and secondary backings and then immediately“sandwiched” between these two backings by compressing marriage rollers.The formed carpet next passes through an oven where water is removedfrom the latex to cure it. The cured latex binds the tufted primarybacking to the secondary backing and the formed laminate carpet is thenready to be installed in a residential or commercial setting.

As one skilled in the art appreciates, the secondary backing isstretched apart by pulling its edges away from each other during theprocessing. In addition there may be some contraction when the secondarybacking is exposed to heat in the curing oven during the manufacturingprocess; however, the opposed edges of the secondary backing are heldstationary relative to each other when subject to this heating andassociated shrinkage. Thus, although the secondary backing contractsfrom the heat during the manufacturing process, its width is maintainedat a set distance so that the dimensions of the carpet remainsubstantially constant.

Another problem, however, arises from the secondary backing beingstretched, namely, stresses develop in the secondary backing and weakenthe final carpet structure. More specifically, the resulting tensionfrom the stretching or pulling of the secondary backing can breakmechanical bonds that its yarns initially form with the latex.

The normal method used to measure the adhesion or holding strengthbetween the secondary backing and the primary backing is to determine“delamination strength.” Delamination strength represents the “peelresistance” characteristics of secondary carpet backing or, stateddifferently, the force required to separate the secondary backing fromthe rest of the carpet.

Another issue related to carpet durability is the tendency of the yarnsto separate from the primary backing, which is the “tuft bind.” That is,tuft bind measures the force necessary to pull the tufted yarn from thelaminate carpet. Among other factors, tuft bind is a function ofdelamination strength. Accordingly, it is desirable for delaminationstrength to be as high as possible to decrease the likelihood ofseparation of the secondary backing from the rest of the carpet,increase resistance to tufts being pulled out of the carpet, and enhancedimensional stability of the carpet.

To achieve suitable delamination strength, the secondary backing shouldbe in intimate contact with the tufted primary backing and backstitchduring the forming and curing process. In addition, the secondarybacking must be firmly bonded with and into the adhesive; otherwise, itwill be easier to pull the secondary backing away from the primarybacking—and correspondingly easier to pluck yarn from the face of thelaminate carpet.

As noted above, however, that secondary backing is pulled tautly duringmanufacturing and then tries to shrink or contract when it is exposed toheat while its edges are maintained at a constant separation distancefrom each other. Based on the dynamics of the shrinkage, the stressesare not evenly distributed across the width of the secondary backing;instead, those stresses are concentrated at the edges of the carpet. Forexample, in a twelve (12) foot wide carpet, approximately eighty percent(80%) of resulting weakness from this shrinkage and associated tensionexists in the area from the edge extending inwardly approximately fourto twelve (4-12) inches. Thus, as those skilled in the art appreciate,the resultant weakness in the formed carpet is most pronounced near itsedges.

To address this problem of low delamination strength adjacent the carpetedges, one attempted solution has been for carpet manufacturers toincrease the weight of adhesive applied to the secondary backing. Theobvious drawback to this manufacturing modification is the correspondingcost increase of the carpet, as adhesive is an expensive component inlaminate carpets. This attempted solution of uniformly increasingadhesive also does not address the differential in strength between theareas adjacent the edges of the carpet and the areas farther inward fromthe edges.

Another attempted solution to this problem has been for carpetmanufacturers to increase the quantity or weight of adhesive appliednear the edges of the secondary backing. For example, carpetmanufacturers may apply adhesive at a rate of an extra two to fourounces per square yard in the area of the secondary backing spanningfrom its edges to six to eight inches inward. As noted above, the extraadhesive increases the cost of the laminate carpet. In addition, thisadditional adhesive applied to the edges may result in uneven curing, asthe edges take longer to cure than the interior sections of the carpet.

Therefore, a need exists in the art to increase effectively thedelamination strength of carpet, particularly near its edges. A needalso exists to be able to increase the delamination strength of carpetat selected areas based on the intended use of the carpet. For example,it may be desired to raise the delamination strength in the center ofthe carpet if it is anticipated that the carpet will be longitudinallycut at that location before use or installation.

SUMMARY OF THE INVENTION

The present invention provides a reinforced secondary backing that maybe used to form a carpet. In the preferred embodiment, the presentinvention comprises the secondary backing fabric and a plurality ofreinforcing yarns interconnected with that fabric. The fabric preferablyhas a plurality of longitudinal or warp extending yarns intermeshed witha plurality of lateral or weft extending yarns that form a scrim ormesh. The reinforcing yarns are interconnected to the fabric to extendsubstantially in the longitudinal or warp direction.

One embodiment of the reinforced secondary backing of the presentinvention comprises a plurality of spaced-apart reinforcing yarnsinterwoven into the fabric. As an example of another embodiment, thereinforced secondary backing comprises non-woven reinforcing fibers thatare joined to the secondary fabric, such as by being needle punched.

The reinforcing yarns preferably have a “rough” texture that providesbetter mechanical adhesion between the adhesive and the reinforcedsecondary backing, as compared to using the secondary material withoutthe reinforcing yarns.

Testing has shown that a laminate carpet formed with a conventional 16×5leno weave secondary backing—a fabric with the warp extending yarnsbeing tape yarns leno woven in pairs and the lateral, weft yarns beingstaple yarns—has a delamination strength near its edges of approximatelytwo and a half to four (2.5-4) pounds. Keeping all other aspects of thecarpet constant except substituting the conventional with the reinforcedsecondary backing—specifically an embodiment using interwoven warpstaple yarns—the delamination strength increases over twenty percent ormore. This increase in delamination strength translates to better andmore desirable carpets.

Of course, if the current delamination strength in the prior artlaminate carpets is acceptable, then the amount of adhesive used to formcarpets utilizing the reinforced secondary backing of the presentinvention can be reduced. Less adhesive translates into a cost savingsboth in terms of materials used and faster production speeds through themanufacturing line (e.g., faster through the carpet coaters and curingoven). As an alternative to decrease price of the final laminate carpet,the pic count of the secondary backing fabric can be reduced if thecurrent delamination strength in the prior art laminate carpets isacceptable.

Also of note, the present invention can be used to selectively targetspecific areas of weakness, such as the areas near the edge of thecarpet that experience the greatest stresses—and correspondingweaknesses—from stretching and heating. Thus, the delamination strengthof the carpet can be made more uniform across its width. In conjunction,using the reinforced secondary backing to increase the delaminationstrength adjacent the edges may remove the need to use an edge coatingof extra adhesive. Since edge coating is usually performed by a secondapplication of adhesive, omitting this step increases the efficiency ofthe manufacturing process. And, leaving out the edge-coating steppromotes more uniform curing of the latex.

It is also contemplated that the reinforcing yarns may be spaced atdesired, set intervals across a portion of the width of the carpet, thusevenly increasing the overall strength of the carpet. A combinationdesign is also contemplated, in which reinforcing yarns are positionedat predetermined intervals across the width of the carpet and additionalreinforcing yarns are further included at locations where weaknessusually exists. For example, one contemplated embodiment of the presentinvention comprises a reinforcing yarn woven or threaded alonglongitudinal rows at one-inch intervals and, for the four to six inchesadjacent each of the edges, there are two to four reinforcing yarninterwoven per inch.

The present invention, accordingly, provides a reinforced secondarybacking that is designed to increase the delamination strength of acarpet formed with it. Ancillary benefits may include improving thedimensional stability of the carpet and increasing the tuft bind.Further benefits potentially include decreasing the manufacturing costsof the carpet by reducing the amount of adhesive used to obtain the sameor greater delamination strength (as compared to a carpet manufacturedwith a corresponding conventional secondary backing fabric).

BRIEF DESCRIPTION OF THE FIGURES OF THE DRAWINGS

FIG. 1 is a partially exploded perspective view of a typical laminatecarpet known in the prior art.

FIG. 2 is a partially exploded perspective view of a carpet formed usingone exemplary embodiment the secondary backing of the present invention,in which the reinforcing yarns are spaced apart at a constant distanceacross the width of the secondary backing fabric.

FIG. 3 is a plan view of the reinforced secondary backing shown in FIG.2.

FIG. 4 is also a plan view showing the reinforcing yarns selectivelylocated in bands at desired positions.

FIG. 5 is a plan view that combines features of the embodiments of FIGS.3 and 4 together.

FIG. 6 is a partially exploded perspective view of another secondarybacking of the present invention that uses non-woven reinforcing fibers.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is more particularly described in the followingexamples that are intended as illustrative only since numerousmodifications and variations therein will be apparent to those skilledin the art. As used in the specification and in the claims, “a,” “an,”or “the” can mean one or more, depending upon the context in which it isused. The preferred embodiment is now described with reference to thefigures, in which like numbers indicate like parts throughout thefigures.

Referring first to FIG. 1, the representation shows a partially expandedperspective view of a typical construction of laminate carpet C. Thecarpet C includes a face portion made up of yarn 22 that has been tuftedinto a primary backing 24 using a process that is well known in the art.The primary backing 24 tufted with yarn 22 is commonly referred to as“griege goods” 20.

While the carpet C illustrated in FIG. 1 shows yarn 22 formed in loops,the present invention is not limited to a particular construction toform the face of the carpet. To that end, other tufted faceconstructions such as cut pile, textured cut pile, and tip sheared, aswell as non-tufted face constructions such as needle punch, woven andfusion bonded, fall within the scope of the present invention. Also, thematerials that form the yarns 22 are often synthetic fibers such asnylon, but may also include polyolefins, polyamides, polyesters,polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT),natural fibers and mixtures thereof. Still other options to form theyarns 22 are naturals or biopolymers.

Likewise, the present invention is not limited to a particular materialor structure to form the primary backing 24. U.S. Pat. No. 4,556,602,which is incorporated herein by reference in its entirety, discloses awoven primary backing. As those skilled in the art appreciate, theprimary backing 24 is typically formed of polypropylene that is woven,but may also be formed of other materials such as polyesters, jute,hemp, composites, blend, nylons, and cottons. Still other primarybacking designs include cellulosic non-wovens and other non-wovens.There are numerous weaves that can be used to form the primary backing,such as plain, twill, and satin. As those skilled in the art appreciate,some common primary backings have the following designations: 24×11;24×13; 24×15; and 24×21.

After being tufted, the greige goods 20 are typically stored on a rollfor later use in another manufacturing line that, for example, maycombine the greige goods 20 with an adhesive 26 and a second backing 30.Typically, the griege goods 20 are removed from a storage roll by beingunwound and horizontally moved upside down so that the reverse of theprimary backing 24 faces upward and is oriented substantially planar orflat. As the greige goods 20 move along the manufacturing line away fromthe storage roll, an adhesive 26, such as latex, is cast or coated ontoits upwardly facing bottom surface.

The latex 26 deposited onto the reverse of the greige goods 20 iscommonly referred to as a “precoat.” Such a process typically uses adoctor blade, which can take the form of a rigid blade, straight blade,or bent blade and is positioned slightly downstream of the location atwhich the precoat is deposited onto the greige goods 20. This doctorblade spreads the latex 26 in the width and height dimensions and alsoadvantageously forces the latex into the tufted yarn 22 on the backsideof the primary 24 for “locking” the components together upon curing. Oneskilled in the art will also appreciate that other precoat applicationmethods can also be used, such as using a roll coater, and the coatingmay optionally be controlled in thickness by either a blade, rod, airknife, or the like. Regardless of the latex application process, apressure roller may also be used downstream of the doctor blade toimprove tuft bind further, which results in preventing removal of carpetyarns 22 from the laminate carpet C face by pulling or snagging.

Although the present invention is not limited to any particular adhesive26, potential latex formulations include vinyl polymers comprisingpolymers or copolymers of hydrocarbon alkenes (including ethylene,propylene, and butylene), acrylonitrile, vinyl acetate, acrylic acid orits alkyl ester, alpha or beta-alkyl acrylic acid or its alkyl esters,including methacrylic acid and methacrylate, styrene, vinylidenechloride, vinyl chloride, and dienes including butadiene. Specific andnon-limiting examples of copolymers include vinyl acetate-ethylene(“VAE”), ethylene-vinyl acetate (“EVA”), styrene-butadiene, latexpolyvinyl chloride, polyvinylidene chloride, vinyl acetate acrylic acid,styrene acrylic acid, acrylonitrile copolymers, or blends of thesecompounds. The precoating may also include flame-retardant filler, suchas aluminum trihydrate, calcium carbonate, barium sulfate, or the like.Such fillers may also be used to reduce latex costs. The precoat mayalso be an extruded “hot melt” material which, when cured and cooled,solidifies and binds the yarns 22 to the primary backing 24. Inaddition, other adhesives known in the art may be used with the presentinvention.

Next in the carpet manufacturing process, the moving web of thepartially formed carpet reaches the location where the secondary backing30 is merged into the precoat 26. The secondary backing 30 typicallycomprises a woven fabric mesh 32, which is sometimes referred to as ascrim. Another example of a secondary backing includes a “fiber batt” inaddition to the scrim, and is disclosed in U.S. Pat. No. 6,344,254,which is incorporated herein by reference in its entirety.

The specific design of the reinforced secondary backing 40 of thepresent invention is discussed in more detail below. One skilled in theart, however, will appreciate that this and other methods forconstructing carpet described herein and other methods may be used witheither the reinforced secondary backing 40 of the present invention or aconventional secondary backing 30; that is, the reinforced andconventional secondary backings 40, 30 may be considered to beinterchangeable in terms of manufacturing carpet.

During the manufacturing process, the secondary backing 30 or 40 isusually unrolled from its storage roll to travel at the same relativespeed as the greige goods 20 to which the precoat 26 has been applied.During this time, the secondary backing 30 is held adjacent its edges byclamps or tracks and is stretched tautly, which is referred to aspre-tenter. Once it is unrolled, the secondary backing 30 or 40 may becoated with an adhesive 26, such as latex. Although the presentinvention is not limited to any particular process to apply the adhesive(if at all), one potential application method uses a skip roll, whichrotates in trough filled with the adhesive 26, and applies the adhesiveto the secondary backing 30 or 40. The quantity of adhesive 26 depositedonto the secondary backing 30 or 40 is typically much lighter than thatapplied to the primary backing 24, for example, approximately one thirdof the weight.

The secondary backing 30 or 40 is then directed to be deposited or laidonto the precoat 26 disposed on the reverse of the greige goods 20.After the adhesive 26 of the secondary backing 30 or 40 engages theprecoat 26 of the greige goods 20, the carpet structure is “sandwiched”together via marriage rollers. The pressure exerted by the marriagerollers promotes the flow of the adhesive 26 into and around the fibersor yarns 20 of the primary and secondary backings 24, 30 or 40 andbetween the tuft stitches. With a woven secondary backing fabric 32, theadhesive 26 usually surrounds the yarns 34, 36 and occupies a portion ofthe interstitial areas formed by those yarns. The adhesive 26 may alsocompletely encapsulate those woven yarns 34, 36 forming the secondarybacking fabric 32.

After exiting the marriage rollers, the moving web of the carpetcomponents are tentered, meaning that the carpet being formed issecurely held at its opposed edges by clamps or frames on the conveyorto ensure that the carpet does not become repositioned or change insize, such as shrinking in width. In fact, when the carpet is tentered,it is stretched so that the width widens (e.g., an approximately twelvefoot wide carpet may be stretched two to four inches in width).

The carpet then passes through an oven, which heats the greige goods 20,secondary backing 30 or 40, and adhesive 26 to a desired temperature.This heating removes water from the adhesive 26 and cures it. The ovensoften heat using an infrared energy source, but may also employ a moreconventional system such as gas heating (such as natural gas) or heatedplates. It is also contemplated using a high-velocity hot-air dryer,which blows hot air to remove the moisture expelled from the adhesive 26during its heating.

The curing process in the oven causes the adhesive 26 to gel and thus tobond or fuse with the primary backing 24, the backs of the yarns 22tufted into the primary backing 24, and the secondary backing 30 or 40.The resultant product from this process is the laminate carpet C or 10.The finished carpet is then cooled and taken up on large storage rollsfor shipment to the customer.

There are other manufacturing processes known by those skilled in theart using a secondary backing 30, all of which the are applicable to thepresent invention. One example is disclosed in U.S. patent applicationSer. No. 10/077,609, which is owned by the same assignee as the presentapplication and is incorporated herein by reference in its entirety.Other examples of such a disclosure include U.S. Pat. Nos. 6,299,715;6,180,166; 5,902,633; 4,849,267; and 4,743,330 and U.S. patentapplication Ser. Nos. 09/993,864 and 10/198,238, all of which are alsoincorporated herein by reference in their entries by reference.

As noted above, the secondary backings typically comprise a woven fabricor mesh 32. The secondary backing fabric has a longitudinal or “machinedirection” known to those skilled in the art as the warp direction W(shown in FIG. 3). The phrase “machine direction” is intended toindicate the direction in which the carpet is tufted. The “filldirection” or “weft direction,” in comparison, is oriented substantiallyperpendicular to the warp orientation W and thus extends laterallyacross the width of the material.

One conventional secondary backing 30 commonly used in the carpetindustry is a woven fabric 32 having tape yarns 34 extending in thelongitudinal, warp direction. A tape yarn is an extruded filament thathas a substantially rectangular cross-section, and thus is alsosometimes referred to as a ribbon yarn. These tape yarns are oftenextruded from polyamides and polyolefins, particularly polypropylene.Because of the tape yarns are generally smooth and generally impervious,latexes and other adhesives do not always form strong mechanical bondswith them. As such, a secondary backing fabric 32 formed exclusively oftape yarns exhibits less than desirable adhesion with the latex 26 andresults in lower lamination strength.

To address this issue, it is common for a conventional secondary backing30 to use a different type of yarn 36 in the weft or fill direction,namely, staple yarns. Staple yarns are made from a multitude ofrelatively short fibers that are spun together to produce a syntheticyarn having a “hairy” appearance. The staple or spun yarns, accordingly,are fiberous, making them more receptive to the latexes and bondingtherewith. Of course, staple yarns may be used in both the warp and filldirections to form the secondary backing, but for economicalconsiderations, spun yarns are typically used only in the weft or filldirection (i.e., the cost of staple yarns is greater than that of tapeyarns). The staple yarns are also commonly formed of syntheticmaterials, again typically polypropylene. However, other plastics andnatural materials, such as jute, may be used to form the staple yarns.

As shown in FIGS. 1-6, in forming a woven secondary backing fabric 32having warp-extending tape yarns 34 intermeshing with weft-extendingstaple yarns 36, it is common to leno weave the tape yarns. That is, aleno weave involves the warp yarns 34 being arranged in pairs and wovenin a manner so that the pairs of warp yarns 34 are twisted between andafter intersecting with each weft yarn 36. The secondary backing fabrics32 formed with warp yarns 34 using a leno weave demonstrate improvedstability when used in a laminate carpet.

Although the present invention is not so limited, it is most common inthe carpet industry to use all synthetic secondary backing fabrics 32using a leno weave pattern with polypropylene tape yarns in the warpdirection and a polypropylene staple yarn in the weft direction. Onesuch scrim 32 often uses a 16×5 weave, in which the warp extending yarns34 use a leno weave and have about 16 ends per inch and the weft yarns36 have about 5 pics per inch. Other common secondary backing fabricscommercially available include the following: 16×3.5; 16×4; 16×6; 18×11;and 18×13.

As those skilled in the art appreciate, the adhesion of these fabrics 32may be further improved by being subjecting to mechanical action such asbrushing, sanding or the like. Generally such mechanical action isconfined to one side of the fabric 32 and the result is to provide a“fuzzier” texture, which has more surface area to which the latex orother adhesive may mechanically bond.

Many secondary backings 30, however, do not bond with the adhesive 26and rest of the laminate carpet C as strongly as desired. To addressthis issue, the present invention comprises a reinforced secondarybacking 40 to which yarns 42 or 44 are interconnected in the generallywarp or longitudinal direction, exemplary embodiments of which are shownin FIGS. 2-6. These yarns are referred to as “reinforcing yarns” 42, 44and assist in forming a stronger bond with adhesives 26 in a laminatecarpet 10. The reinforcing yarns 42 or 44, in fact, provide and add moresurface area so that the latex 26 or other binder material used to jointhe secondary backing 40 to the primary backing 24 has more locations orplaces to which the adhesive 26 can adhere. This stronger bondcorrespondingly increases the delamination strength of the formedlaminate carpet 10.

The reinforcing yarns 42, 44 used with the present invention may be anyknown yarn. The preferred yarn is a staple yarn as a result of itstexture and associated bonding ability with the adhesive. However, yarnsbesides staple yarns may be used, including, but not limited to,monofilament yarns having an exaggerated crimp, contoured shape, ortextured exterior adapted to create additional surfaces and intersticesto which the adhesive may adhere. In particular, it is contemplatedusing a tape yarn that has been fibrillated to have more texture, suchas a courser consistency and irregular shapes in its surface to providean improved bonding surface with the adhesive. Still other contemplatedreinforcing yarns include entangled yarns, knit-de-knit crinkle yarns,and core-bulked yarns.

The reinforcing yarns 42, 44 may be formed of virgin materials, 100%recycled materials, or a mixture of virgin and recycled materials in anydesired and suitable range. The yarns may also be formed of othersynthetic or natural materials, as desired.

In one preferred embodiment of the present invention, the reinforcingyarns 42 are preferably woven or threaded into a secondary backingfabric 32 that is substantially uniform and symmetrical, which is shownin FIGS. 2-5. For example, the reinforcing yarns 42 may be interwoven atthe same time that the secondary backing fabric 32 is being produced.

In another embodiment shown in FIG. 6, the reinforcing yarns 44 comprisea non-woven material joined to the secondary backing fabric 32, forexample by being needle punched thereto. The non-woven materials usedmay comprise any type of desired non-woven material, either natural orsynthetic, such as PET, polyethylene, polyester, or nylon. Other optionsinclude fibers, hairs, or a jute-like material, and may be either virginor recycled materials.

It is also to be appreciated that the present invention is not intendedto be limited to any particular design of a secondary backing fabrics32.. For example, the fabric 32 may be woven, knitted, point bonded,thermal fused with use of low melted fibers and other processes can beemployed to manufacture a viable secondary backing for use inconjunction with the present invention. Still another option is to usethe present invention with a fabric that is connected to a fiber batt,as disclosed in U.S. Pat. No. 6,344,254.

As noted above, it is preferred that the reinforced secondary backing 40of the present invention—regardless of the embodiment or design—be usedin the same manner as a conventional secondary backing 30 to form alaminate carpet. Thus, as with any typical carpet C, a laminate carpet10 of the present invention would include the following components: aprimary backing 24; yarn 22 tufted into the primary backing 24; thereinforced secondary backing 40; and an adhesive 26 disposedintermediate the primary backing 26 and the secondary backing 40. Thepresent invention also includes a method of manufacturing orconstructing a carpet 10 using the reinforced secondary backing 40.

Now referring back to FIGS. 2-5, the reinforcing yarns 42 are woven inthe fabric 32 to generally extend longitudinally in the warp direction.When considering these illustrated embodiments and others, the quantityand types of reinforcing yarns 42 needed for the present invention todemonstrate an increase in delamination strength is a function of manyvariables. For example, a major consideration is the type of adhesive 26used. As one skilled in the art will appreciate, each reinforcing yarn42 will have more impact with a hot-melt adhesive than with heat-curablelatex. As such, fewer reinforcing yarns 42 will achieve a desiredincrease in delamination strength with a hot-melt adhesive compared toheat-curable latex. Other factors that also vary the quantity or numberof reinforcing yarns 42 need to obtain a desired increase indelamination strength include the type of reinforcing yarn 42 used; thematerials used to form the reinforcing yarn 42; the size of the yarn(s)22 or 42; he type of primary backing 24; the type of secondary backingfabric 32; the materials used to form the primary and secondary 24, 32;the weaves used to manufacture the primary and secondary 24, 32; thetype of yarn 22 used to form the face of the carpet 10; the tuftingpattern of the yarn 22; and other factors appreciated by those skilledin the art. Thus, it is within the scope of the present invention forthose skilled in the art to vary the quantity of reinforcing yarns 42used and their positioning in the secondary backing fabric 32 from theexemplary embodiments discussed or illustrated herein.

As was noted above, it is common in conventional secondary backings 30for the warp extending yarns 34 of the fabric 32 to be tape yarns andthe weft extending yarns 36 to be staple yarns. Thus, when the preferredembodiment of a staple yarn is used as the reinforcing yarn 42 as shownin FIGS. 2-5, the staple yarn is disposed between warp rows formed oftape yarn 34 and interweaved around the weft-extending staple yarns 36that form the fabric 32.

Referring now to FIG. 3, the reinforcing yarns 42 are spaced apart fromeach other across at least a portion of the fabric 32 at a distance ofone and a half inches or less. Alternatively, the reinforcing yarns 42may be spaced apart from each other at approximately one-inch intervals.Other separation distances between reinforcing yarns 42 are alsocontemplated, such as a quarter inch, half inch, three-quarters inch,two inches, three inches, and separations falling between those listeddistances. As those skilled in the art appreciate, however, economicconsiderations make a design woven in smaller increments less viablebecause of the number of the reinforcing yarns needed to be interwoven,but it is nevertheless within the scope of the present invention.

FIGS. 2-5 show the reinforcing yarns 42 as individual yarns and eachyarn is woven or threaded into a single warp-extending row of the fabric32. Thus, the reinforcing yarns 42 in these embodiments extend exactlywarp-wise and there is one single reinforcing yarn 42 interwoven alongand into a given row. As such, the reinforcing yarns 42 in theseembodiments are laterally spaced apart from each other at least thedistance of one warp extending yarn 34 of the secondary backing fabric32. Nonetheless, there may be more than one reinforcing yarn 42interwoven along and into one single row within the scope of the presentinvention, but the associated cost generally outweighs the advantages ofsuch a design.

It is also contemplated having a plurality of the reinforcing yarns 42disposed in one or more respective bands 50, 52. Such a band 50, 52extends in the weft direction a distance less than half of the width ofthe fabric 32 and includes at least two reinforcing yarns 42. Referringnow to FIG. 4, each of the bands 50, 52 may be one inch in width andthere are at least two reinforcing yarns 42 in each band.

The bands 50, 52 of the reinforced yarns 42 may be positioned atlocations where increased stresses arise or are created in the carpet 10either from use or in manufacturing. For example, as discussed above,the secondary backing fabric 32 is stretched in the pre-tenter to asmall degree and then stretched more substantially in the tenter stage.This stretching creates stresses. Then, in addition, secondary backingfabrics 32 contract in size when exposed to heat in the manufacturingprocess, primarily in the curing oven. During these times when thesecondary backing fabric 32 is heated, its opposed edges are heldstationary relative to each other by the tenter device to maintain itswidth constant. The resulting tension from the stretching and theshrinkage of the secondary backing material thus can break mechanicalbonds formed with the adhesive 26, which translates into a weakercarpet. The most pronounced weakness from these manufacturing stressesis near the edges of the carpet.

The bands 50, 52 of reinforced yarns 42 can be selectively placed at thelocations where the carpet 10 is weakened, so one embodiment of thepresent invention includes two of the bands that are each respectivelydisposed adjacent the opposed edges 38 of the fabric 32. Those twobands—the edge bands 52—may be spaced approximately one to three inchesfrom their respective edge of the manufactured carpet in FIGS. 4 and 5.The reason for this spacing contemplates that a portion of the carpetadjacent its edges will be removed and discarded as selvage waste, whichis usually about an inch for a twelve-foot wide carpet. Thus, with theedge bands 52 being spaced approximately one inch from their respectiveedge, the edge bands 52 are adjacent the actual edge 38 of the carpet 10after the trimming process is completed.

As another example, a band of the reinforcing yarns may be located inthe center of the carpet if it is anticipated that the carpet will becut in half after manufacturing (i.e., a twelve-foot wide carpet cutinto two six-foot wide sections). This cutting would be an additionalstress and the present invention may increase the delamination strengthof the carpet at this taxed area. Those skilled in the art will alsoappreciate that bands may be selectively positioned at other areas orregions of the carpet that have a tendency to be weak or fail frommanufacturing or subsequently arising stresses.

In locating these bands 50, 52, one skilled in the art will furtherappreciate that there are different variations as to the dimensions of aband and the number of reinforcing yarns 42 included within a givenband. For example, if the band 50, 52 is one inch in width, it iscontemplated using at least two reinforcing yarns 42 in the band or evenusing four or more reinforcing yarns 42 in that one-inch band. Asanother alternative, the reinforcing yarns 42 may be interwoven into atleast every fourth warp-extending row of the fabric 32 or otherrepeating sequence. Still another option is to space the reinforcingyarns 42 apart at approximately one-inch intervals within the band, inwhich the band is wider than one inch, as shown by the innermost band 50illustrated in FIG. 5.

It is also contemplated that not all of the bands 50, 52 are uniform inthe number of reinforcing yarns 42 or their width. As an example shownin FIG. 4, there may be four additional reinforcing yarns 42 for thefirst inch of width adjacent the edge 38 and only two to threeadditional reinforcing yarns 42 are included per inch in the remainderof the bands 50 moving toward the center.

Yet another variation of the present invention includes reinforcingyarns 42 at a constant spacing (i.e., one-inch intervals) across thewidth of the fabric 32 (as shown in FIGS. 2 and 3) and, in addition,selectively includes bands 50 of the reinforced yarns 42 at points ofincreased stress or weakness (as shown in FIG. 4). As an exemplaryillustration shown in FIG. 5, one contemplated design includes thereinforcing yarns 42 spaced at one-inch intervals across the majority ofthe width of the fabric 32 and also includes bands 50, 52 with a higherconcentration of reinforcing yarns 42 positioned at locations wherelower delamination strengths or other weaknesses typically arise, i.e.,adjacent the warp-extending edges 38 of the carpet 10.

Additionally, the reinforcing yarns 42 may be colored, if desired. Suchcoloration of the reinforcing yarns may serve as carpet pattern guide asdisclosed in U.S. Pat. No. 5,484,639, which is incorporated herein byreference in its entirety. The coloration of the reinforcing yarns 42may also be used for marketing purposes.

Referring now to FIG. 6, another embodiment of the present invention isshown, in which the reinforcing yarns 44 comprise a non-woven materialjoined to the secondary backing fabric 32. Again, the reinforcing yarns44 are directed generally in the warp direction. To join the reinforcingyarns 44 and the secondary backing fabric 32, any means known in the artcan be used, including, for example, needle punching. More specifically,in one manufacturing method, the secondary backing fabric 32 is placedon a surface and the reinforcing yarns 44 comprising non-woven fibersare laid on top of the fabric 32. The reinforcing yarns 44 and thefabric 32 are then needled together. This process may be automated andcontinuous. Also, other joining methods know in the art can be used.

Still referring to FIG. 6, placement of these non-woven reinforcingyarns 44 may be at selected locations extending generally in the warpdirection and spaced apart from other reinforcing yarns 44 (or bundlesthereof). The reinforcing yarns 44 of this embodiment are positionedduring manufacturing of the carpet 10 so that they are disposed into theadhesive 26 before the underlying fabric 32 merges into the adhesive.Stated differently, the non-woven reinforcing yarns 44 are disposedcloser to the primary backing 24 than the fabric 32 connected to thoseyarns 44.

When a carpet 10 is manufactured or constructed using the reinforcedsecondary backing 40 of the present invention, the resultant product mayprovide a marked improvement in delamination strength over a carpet Cmade with a conventional secondary backing 30. This increase indelamination strength may be over ten percent and possibly rise tofifteen percent, twenty percent, thirty percent, fifty percent, or evenexceed seventy percent. Such an improvement in delamination strength isdetermined or evaluated by comparing the measured value for a carpet Cformed using a fabric 32 that does not include the reinforcing yarns andanother carpet 10 using the exact same backing fabric design 32 with thereinforcing fibers 42 or 44 interconnected thereto. All other variableare maintained constant, including the adhesive 26 used, its applicationmethod and quantity, curing times and temperatures, the greige goods 20used, etc. Stated differently, the two carpets C, 10 being compared aremanufactured on the same line—preferably sequentially—maintaining allvariables constant except the secondary backing, in which onemanufacturing run uses the reinforced secondary backing 40 of thepresent invention and the other run uses the same secondary fabric 30without including the reinforcing yarns 42 or 44.

To that end, comparative testing has been conducted evaluating carpets10 manufactured using the secondary backing 40 of the present inventionto similarly manufactured and constructed carpets C that did not employthe reinforcing yarns 42. As is known in the art, a tuftingmanufacturing process was used, in which the primary backing 24 wastufted using a 3/16-pattern loop pile machine. More specifically, theprimary backing 24 was a 28×13 pic polypropylene material that wastufted with yarn 22 formed of 2407/3 polypropylene in a high-lowpattern. The latex 26 used was manufactured by BASF® sold under thetradename Style 6650, and approximately thirty-four (34) ounces persquare yard were applied between the primary and secondary backings. Theoven operated at a temperature of about 425° F. and the respectivecarpets 10, C were each heated for approximately five to six (5-6)minutes.

As to the secondary backing fabric 32, both carpets used a 16×5 mesh(warp extending yarns leno weaved and having about 16 ends/inch and theweft yarns having about 5 pics/inch). The warp extending yarns 34 of thefabric were tape yarns and the weft extending yarns 36 were stapleyarns, all of which were formed of polypropylene. This secondary backingis sold under the tradename BetterBack® designated as Style number1003634. Of note, the secondary backings 30, 40 were mechanically“brushed” to increase its bonding strength.

The carpet 10 that included the reinforced yarns 42 used staple yarnsformed of polypropylene interwoven into the secondary backing 32. Therewere two (2) reinforcing yarns evenly spaced per inch. During themanufacturing, the closest reinforcing yarn to one edge of the secondarybacking fabric was approximately three (3) inches away and thereinforcing yarns 42 were incrementally interwoven from there movinginwardly toward the center of the carpet a distance of eight (8) inches.The reinforcing yarns 42 were each respectively interwoven into andalong a single warp-extending row. Once the selvage waste was removedfrom the edge of the manufactured laminate carpet, the outermostreinforcing yarn 42 was immediately adjacent the new edge and locatedbelow the first tufted warp-extending row of yarn 22. The reinforcedsecondary backing 40 of the present invention was brushed after thereinforcing yarns were woven into the secondary backing fabric.

Given these parameters, the charts below provide the measureddelamination strength for a control carpet and a carpet using thereinforced backing of the present invention: CONTROL CARPET TRIALAVERAGE NUMBER SIDE 1 SIDE 2 LBS PULL 60403 2.6 3.0 2.8 LBS 72303 4.23.0 3.6 LBS

CARPET WITH REINFORCED BACKING TRIAL AVERAGE NUMBER SIDE 1 SIDE 2 LBSPULL 60403 5.7 5.5 5.6 LBS 72303 5.1 4.7 4.9 LBSAll measurements are listed in pounds.

As those skilled in the art appreciate, delamination strength ismeasured using a “Resistance to Delamination of the Secondary Backing ofPile Yarn Floor Covering” procedure. The accepted testing protocol inthe art is ASTM D 3936-00, which was published in approximately April2000. However, this delamination measuring procedure was modified whenconducting the above measurements (using a variation that the assigneeuses as a matter of course). That is, the ASTM D 3936-00 procedureinstructs to take one test specimen near the edge “but no nearer to theextreme edge than 5% of its width, and take one specimen from the centerarea.” The testing above was performed starting at what was referred toas the “extreme edge,” as this more accurately reflects the carpet'sstrength to withstand the environmental stresses, strains, and forcesexperienced after installation.

The ASTM “Resistance to Delamination” protocol specifies thatapproximately three inches of the specimen is to be delaminated in thetest. As one skilled in the art appreciates, a comparison between carpet10 formed with the reinforced secondary backing 40 and conventional,control carpet C would not be indicative of the increase in strengththat the present invention potentially offers if there were noreinforcing yarns 42, 44 in that portion of the specimen beingdelaminated. Stated differently, delamination tests comparing a carpetformed with a conventional secondary backing 30 and one formed with thereinforced backing 40 would not be telling if the section of carpettested did not include any reinforcing yarns.

Given the testing results and parameters provided above, the carpet 10formed with the reinforced secondary backing 40 of the present inventionshowed an increased resistance to delamination over the conventional,control carpet C.

Although the present invention has been described with reference tospecific details of certain embodiments thereof, it is not intended thatsuch details should be regarded as limitations upon the scope of theinvention except as and to the extent that they are included in theaccompanying claims.

1. A reinforced secondary backing, comprising: a. a woven fabric havinga plurality of substantially parallel warp extending yarns and aplurality of substantially parallel weft extending yarns, in which thewarp and weft yarns are oriented transversely to each other, the warpyarns defining longitudinal rows therebetween, the fabric having opposedlongitudinal edges extending in the warp direction that define a widththerebetween; and b. a plurality of reinforcing yarns interwoven intothe fabric and extending substantially in the warp direction, theplurality of reinforcing yarns comprising a band of reinforcing yarns,in which the band extends in the weft direction a distance less thanhalf of the width of the fabric.
 2. The secondary backing of claim 1,wherein there are at least two bands.
 3. The secondary backing of claim2, wherein each of the bands is one inch in width and there are at leasttwo reinforcing yarns in each band.
 4. The secondary backing of claim 3,wherein two of the bands are each respectively disposed equal distantfrom the opposed edges of the fabric, those two bands being the edgebands.
 5. The secondary backing of claim 4, wherein the edge bands arespaced approximately one inch from their respective edge.
 6. Thesecondary backing of claim 1, wherein the reinforcing yarns of each bandare respectively interwoven into at least every fourth row.
 7. Thesecondary backing of claim 1, wherein the band is one inch in width andthere are at least two reinforcing yarns in the band.
 8. The secondarybacking of claim 1, wherein the band is one inch in width and there arefour reinforcing yarns in the band.
 9. The secondary backing of claim 1,wherein the reinforcing yarns are spaced apart at approximately one-inchintervals in the band.
 10. The secondary backing of claim 1, wherein therespective reinforcing yarns each extend along a single row and arewoven about weft yarns.
 11. The secondary backing of claim 1, whereinthe fabric is a mesh in which the warp extending yarns use a leno weaveand have about 16 ends per inch and the weft yarns have about 5 pics perinch.
 12. The secondary backing of claim 1, wherein the reinforcingyarns are staple yarns.
 13. The secondary backing of claim 12, whereinthe warp extending yarns of the fabric are tape yarns and the weftextending yarns are staple yarns.
 14. A reinforced secondary backing,comprising: a. a woven fabric having a plurality of substantiallyparallel warp extending yarns and a plurality of substantially parallelweft extending yarns, in which the warp and weft yarns are orientedtransversely to each other, the fabric defining a width in the weftdirection; and b. a plurality of spaced-apart reinforcing yarnsinterwoven into the fabric and extending substantially in the warpdirection, and the reinforcing yarns laterally spaced apart from eachother one and a half inches or less.
 15. The secondary backing of claim14, wherein the reinforcing yarns are spaced apart from each other atapproximately one-inch intervals.
 16. The secondary backing of claim 14,wherein the fabric is a mesh in which the warp extending yarns use aleno weave and have about 16 ends per inch and the weft yarns have about5 pics per inch.
 17. The secondary backing of claim 14, wherein thereinforcing yarns are staple yarns.
 18. The secondary backing of claim17, wherein the warp extending yarns of the fabric are tape yarns andthe weft extending yarns are staple yarns.
 19. A reinforced secondarybacking, comprising: a. a fabric having opposed longitudinal edgesextending in the warp direction that define a width therebetween; and b.a plurality of reinforcing yarns interconnected with the fabric andextending substantially in the warp direction, wherein, when the fabrichaving the reinforcing yarns interwoven therein is adhesively bonded toa tufted primary backing to form a laminate carpet, the carpet has adelamination strength at least twenty percent greater than a similarlyformed carpet constructed using the fabric without the reinforcing yarnsinterwoven therein.
 20. The secondary backing of claim 19, wherein thedelamination value is thirty percent greater using the fabric having thereinforcing yarns interwoven therein.
 21. The secondary backing of claim19, wherein the reinforcing yarns are disposed in a respective bandlaterally extending one inch in width across the fabric, each bandincluding a plurality of reinforcing yarns.
 22. The secondary backing ofclaim 21, wherein there are at least three reinforcing yarns in eachband.
 23. The secondary backing of claim 21, wherein two of the bandsare each respectively disposed equal distant from opposed edges of thefabric.
 24. The secondary backing of claim 21, wherein in each band, thereinforcing yarns are disposed in at least every fourth row of thefabric.
 25. The secondary backing of claim 19, wherein the reinforcingyarns are spaced apart from each other at approximately one-inchintervals.
 26. The secondary backing of claim 19, wherein thereinforcing yarns each extend along a single respective warp row in thefabric.
 27. The secondary backing of claim 26, wherein the warpextending yarns of the fabric are tape yarns and the weft extendingyarns are staple yarns.
 28. The secondary backing of claim 27, whereinthe reinforcing yarns are staple yarns.
 29. The secondary backing ofclaim 27, wherein the fabric is a mesh in which the warp extending yarnsuse a leno weave and have about 16 ends per inch and the weft yarns haveabout 5 pics per inch.